Regulated Breathing System

Abstract

A demand-regulated breathing system; more particularly, a system for supplying life support gases to one or more divers from a diving bell wherein the volume of the intake and exhaust gas to and from each diver is controlled by valves operated by a system of levers coupled to a diaphragm in the wall of the diver's mask.

Description

BACKGROUND OF THE INVENTION

This relates in general to regulated breathing systems; and more particularly, to a self-regulated closed cycle breathing system for deep sea divers.

For deep sea diving it is customary for divers to work out of a pressurized chamber maintained aboard the ship which accompanies and services the divers. This enables the divers to continue in a high pressure environment between dives and to decompress slowly in order to avoid compressed air illness, due to too rapid ascent from deep water. Such a chamber is often designed so that one end may be sealed off and the smaller chamber so formed may be lowered separately into the sea to serve as a diving bell and life support chamber for one or more deep sea divers. When the diving bell has reached the desired depths the divers emerge through hinged doors at the bottom, through which they are connected to the life-support system by noncollapsible hoses. Although containers constituting the primary source of breathing gas are usually located aboard the accompanying ship, the compressor and decompressor, filters, and other elements of the life support system may be installed in the diving bell in which the divers are lowered to the working level.

Although initially ordinary air was employed in the divers' breathing apparatus, the proposal was made some years ago by Prof. Elihu Thompson, F.R.S., to use helium instead of oxygen in the life-supporting mixture of gases supplied to the divers. This was successfully demonstrated by the Government Bureau of Mines U.S.A., and is now a commonly used expedient. The reason that helium is preferred over nitrogen for this purpose, is that helium has a solubility in water which is nearly 40 percent less than that of nitrogen, and, its rate of diffusion is 2.64 that of nitrogen. Thus, nearly 40 percent less of helium than of nitrogen will be dissolved in the watery parts of the body; and further, helium will escape more quickly from the lungs during decompression. It is estimated that using helium, the decompression periods are reduced in the ratio of one-third to one-fourth, compared to a system using an ordinary air mixture containing nitrogen, thus providing a substantial advantage.

In most prior art systems, the life-supporting gas is supplied to the divers through an open or semiclosed system, in which at least a portion of the gas exhaled by the diver is bubbled out through the water, and lost. Whereas the loss of gas to the atmosphere is of no economic importance when air or a nitrogen mixture is used for the life support system, it assumes substantial economic importance when helium is used as a component of such a mixture.

Moreover, in many prior art systems of the semiclosed, self-contained types, carbon dioxide accumulations in the breathing equipment require that the diver carry on his person bulky carbon dioxide scrubbing equipment. This limits the usefulness of the system to about 3 hours, which duration is limited by the capacity of the usual carbon-dioxide-absorbent canister.

It is further apparent that many prior art breathing systems of the semiclosed or self-contained types are manifestly unsafe, in view of the fact that the diver may become unconscious from over accumulations of carbon dioxide before he is aware of the problem.

Accordingly, it is the object of the present invention to provide improvements in closed cycle breathing systems, more particularly of the type used for life support systems for deep sea divers.

More particular objects of this invention are to provide a closed cycle breathing system which is more economical to operate than the systems provided by the prior art, less bulky for the diver, adapted for longer periods of use, and which may be used with greater safety.

BRIEF DESCRIPTION OF THE INVENTION

The foregoing objects are realized in accordance with the present invention in a life-support system including a closed circuit breathing cycle in which the flow of life supporting gas to a breather is controlled by a double-acting demand regulator which operates in response to the inspiration and expiration of the breather.

More particularly, the system in accordance with the present invention is designed for use in conjunction with a deep sea diving apparatus in which divers lowered to a working level below the surface of the water are supplied through interconnecting hoses from a life support chamber including compressors, decompressors, and filters for supplying a breathing mixture of pressurized, purified gas, under control of a regulator which responds to the inhalation and exhalation of the diver. The stream of exhaled breathing gas passes back into the life support chamber, is filtered, decompressed, and returned to the source for recirculation.

The regulator, which is a salient feature of the system, comprises a flexible diaphragm which is incorporated in a wall of the chamber formed by the breather's mask. To the central portion of the diaphragm is rigidly connected a fitting which engages a roll pin. The latter acts as the fulcrum for a system of levers, which is actuated upon inhalation of the diver to open a valve for intake of a life-supporting gas stream, and to close a valve for exhaust of the returning gas; and upon expiration of the diver, to open the exhaust valve and close the intake valve. Preferably, the life-supporting stream is a mixture comprising a major portion of helium, with the balance consisting essentially of oxygen and nitrogen. A baffle connected near the intake valve limits the recirculation of carbon dioxide through the mask.

The system may include an auxiliary source of gas which can be manually connected to the mask through the regulator, in case of emergency.

Advantages of the closed, demand-breathing-controlled system of the present invention are as follows:

1. No gas is lost to the atmosphere in the process, providing an outstanding economic advantage where helium is used as a major component.

2. The diver is required to carry less bulk, since no carbon dioxide scrubbing canister, or large gas supply cylinders are required, only a small emergency supply being carried, if desired.

3. A diver using the disclosed system can remain in the water as long as physical endurance permits, as there is no limitation imposed by the capacity of a carbon-dioxide-absorbent canister, as in prior art systems.

4. Failure in the disclosed system is immediately evident to the diver, as he has time (though possibly short) to correct or circumvent possible malfunction. This is not possible with semiclosed or self-contained types of equipment of the prior art, in which the diver may not be aware of failure in carbon dioxide removal before he loses consciousness.

These and other objects, features, and advantages will be apparent to those skilled in the art by a study of the specification hereinafter in connection with the attached drawings.

SHORT DESCRIPTION OF DRAWINGS

FIG. 1 shows a diver equipped with a demand breathing apparatus in accordance with the present invention, emerging from a diving bell;

FIG. 2 is a showing in schematic of a closed cycle breathing system in accordance with the present invention;

FIG. 3 is a detailed perspective showing of a diving mask including a demand breathing apparatus in accordance with the present invention;

FIG. 4A is an end-on view, with cover and diaphragm removed, of the demand regulator assembly for the closed cycle breathing system in accordance with the present invention; and

FIGS. 4B and 4C are sectional showings of the demand regulator assembly along the planes in FIG. 4A indicated by the directional arrows.

Referring, now, to FIG. 1 of the drawings, there is shown a diving bell 3 of a conventional type well known in the art. In the present example, assuming the working level is about 200 feet below the surface of the sea, and that a pair of divers 1 and 2, are to be accommodated, this may comprise a sphere of steel, 7 feet in inner diameter and having walls of, for example eleven-sixteenths inch thick. This may include an opening at the bottom about 7 feet square covered by a removable hatch cover 3A, which is large enough for a diver to emerge into the water, together with life-supporting hose and auxiliary equipment.

The bell 3 is lowered to the desired depth by means of a steel cable 20 formed of flexible braided strands to a thickness of three-fourth inch in cross section, which is designed to sustain a force of about 40,000 pounds without failure. The upper end of cable 10 is preferably wound about a capstan aboard the servicing ship, which raises or lowers it to the desired level. In addition to the cable 10, the diving bell 3 is also connected to shipboard by means of a noncollapsible flexible hose 9, comprising, for example, a smooth, nontoxic synthetic, impervious to oxygen, helium and nitrogen gas mixtures. The hose 9 includes a telephone line, a pair of conduits for carrying the life-supporting gas to and from the bell, electrical service leads for supplying power to the bell for lights, compressor motors, etc., and other electrical leads which are attached to monitoring equipment in the bell. In the example under description, one of the following mixtures may be employed as preferred for the purposes of the present invention:

Gas Type 1 Type 2 __________________________________________________________________________ 0.sub.2 4% 9% N.sub.2 11% 25% He 85% 66%.

However, it will be understood that ordinary air, and other life-supporting gaseous mixtures may be employed The gas is maintained at a temperature within the range 80.degree. to 90.degree. Fahrenheit at the diver's depth; and, the equipment should have a flow capacity of 5 actual cubic feet per minute, at that depth.

Equipment including a compressor 7 and a decompressor 8, filter, regulator, etc., which will be presently described in greater detail, may be located within the diving bell 3. A decollapsible hose 6, which is substantially similar to the hose 9 described above, houses a pair of inhale and exhale conduits which are connected to the face mask 4 of diver 2 through the demand regulator system 5.

Let us refer, now, to FIG. 2 which is a schematic showing of a typical gas circuit in accordance with the present invention.

The gas storage chamber 20, may comprise, for example, a steel shell, which may, for example, by cylindrical in shape, and which in the present example has a capacity of 525 cubic feet. The mixture of life-supporting gas, referred to above, is usually maintained during storage at a pressure of 2,000 pounds per square inch absolute.

A valve 19, which is a conventional type, controls the outlet from storage tank 20 to conduit 9a which is the intake conduit into the diving bell 3 and the life support equipment servicing the divers 1 and 2.

The intake line 9a conveys a stream of gas, flowing at the rate of 1 to 5 actual cubic feet per minute, depending on demand, at a temperature approximating 85.degree. Fahrenheit into muffler 21, which serves to deaden the sound of the apparatus. The temperature of the incoming gas is regulated topside so that it will be suitable for the divers' physical comfort. The gas stream is then passed through the filter 22, which serves to filter out solid particles, which would tend to clog the compressors and valves of the system.

The compressor 7, which may be combined with the decompressor 8, is designed to be oil and contaminant free, and to operate in a chamber in which the internal pressure may vary from 50 to 200 pounds per square foot absolute, depending on the submerged depth. The inlet pressure of the compressor 7 equals the ambient pressure in the bell, which depends on the submerged depth of the diving bell 3. In the disclosed example, assuming the diving bell 3 is at a depth of 200 feet, the ambient pressure would be 103.7 pounds per square inch absolute. The discharge pressure, which is maintained at a pressure differential of 75 pounds per square inch absolute above the inlet pressure, is 178.7 pounds per square inch absolute, in the disclosed example. In preferred form, the compressor 7 should be capable of delivering from 0 to 3 actual cubic feet per minute at the operating depth. Furthermore, compressor 7 should preferably be capable of operating off of either a 115 or 230-volt, 60-cycle-per-second power line, at a contemplated power consumption of 820 watts.

An apparatus which has been found to be suitable for operation for the purposes of the present invention either with air, or with the helium mixtures described, is manufactured by ZEFEX, INC. of 5600 Pike Road, Rockford, Illinois, and is described in their bulletin No. 118-2.

The gas stream flowing from the compressor 7 passes through heat exchanger 24, where it is reduced in temperature from 275.degree. to 95.degree. Fahrenheit. Heat exchanger 24 may assume any of the forms well known in the art.

The stream of gas next passes through a conventional filter 25. Filter 25 serves principally for the purpose of removing foreign particles.

The life support gas stream next passes through a conventional differential pressure gauge 26, which is designed to measure pressure differentials over a range 0--200 pounds per square inch between the gas stream moving into the outgoing conduit 6a, and the ambient environment within the bell 3. The gauge 26 is automatically set to actuate an escape valve mechanism 26a when the pressure of the gas stream flowing into hose 6a exceeds that in the gas chamber 3 by more than 85 pounds per square inch.

A valve 27, which is of a conventional type, permits the gas supply between the diving bell 3 and the divers' lines to be controlled manually, or to be shut off altogether when the diving equipment is not in use.

The line 6a passes into the diver's mask 4 through the intake valve 5a of the inhalation regulator 5. The diver's hoses 6a and 6b are noncollapsible, flexible tubes, preferably comprising a smooth, nontoxic synthetic, impervious to oxygen, helium and nitrogen gas mixtures. This may be of a type manufactured, for example, by Hewett-Robbins, Incorporated, a Division of Litton Industries, to specification No. 23-0152, disclosed in their catalogue No. 4102A-10-G-567, copyright 1967. In the example, under description, the hose is reinforced with twin braids of high tensile synthetic cord to limit the hose contraction under pressure. It has an inside diameter of one-half inch, an outside diameter of sixty-one sixty-fourths of an inch, and a weight per foot of 3 lbs. in air, and zero in water.

FIG. 3 is a perspective showing of the diver's mask 4 in combination with the demand regulator system 5. It will be apparent that the regulator system 5 is incorporated into the diver's suit in a manner to provide a fluidtight compartment, one wall of which comprises a diaphragm, which compartment is connected by a small auxiliary coaxial hose to the mouth and nose portions of the diver's mask. FIGS. 4A, 4B, and 4C are detailed showings of the demand regulator system 5, which will be described hereinafter with greater particularity.

The gas exhausted from the diver's mask 4 passes out through the valve 5b of the demand regulator system, through the back-pressure-actuated valve 79, and through the return hose 6b, which passes back into the diving chamber 3. The conventional valve 28 is manually operative, and similar in function to the valve 27, for manual control of complete cutoff, when not in use, of the flow of gas from the diver's mask 4.

The returning gas stream, containing exhaust gases including carbon dioxide from the lungs of the diver, passes through a conventional water trap 29. The water level indicator is set by means of a conventional float arrangement, to actuate an alarm 30 when the water in the water trap 29 rises to such a level that water content of the returning gas might conceivably damage the compressors or other equipment.

The exhaust stream then returns through a differential pressure gauge 32, which is substantially similar to the pressure gauge 26, except that it is adapted to operate to measure a pressure differential over a more restricted range of from 0 to 70 pounds per square inch. The pressure differential between the returning exhaust and the ambient environment in the bell 3 is automatically maintained at 30 pounds per square inch by means of the pressure controlled relief valve 32a.

The returning stream then passes through conventional filtering system 34, placed there for the protection of decompressor 8 for removal of foreign particles which might have entered the exhaust system.

The filtered exhaust gas stream then passes into the decompressor 8, which operates under the same environmental conditions as the compressor 7. It is preferably designed to operate at a suction pressure equal to from 30 to 40 pounds per square inch absolute below the unit discharge pressure, equaling the ambient pressure of chamber 3, which varies from 50 to 200 pounds per square inch absolute, depending on the chamber's submerged depth. The flow range of the decompressor 8 is preferably capable of a suction flow of from 0 to 5 actual feet per minute at the depth of operation. If desired, the compressor and decompressor can be combined in a single housing. Either unit may take the form, for example, of that manufactured by the ZEFEX, INC. of 5600 Pike Road, Rockford, Illinois, and disclosed in their bulletin No. 118-2.

After decompression to a pressure of 103.7 pounds per square inch absolute, assuming the operating level is 200 feet below the surface, the stream of returning gas is passed through the muffler 35. This is similar in form to muffler 21 in the intake circuit, and serves to reduce the exhaust noise level.

The gaseous stream is then returned to the storage tank 20 aboard ship, for recirculation and purification. At this point the composition, temperature, and pressure of the gas is retested, additional gas being added, if necessary, to meet the criteria for the desired mixture.

An auxiliary portable gas source 36 is provided to be carried on the back of the diver, in case the principal gas supply fails. This may comprise a small tank, having a capacity of approximately 3 minutes' supply of breathing gas of the same composition as the principal supply. Auxiliary tank 36 is manually opened for operation by means of the normally closed valve 37, passing a stream of gas through a second normally closed valve 38 to the junction 39. From junction 39, the auxiliary stream flows through the intake valve 5a of the regulator system 5, and into the diver's mask 4, in the manner previously described.

Let us refer, now, in more detail to the demand regulator assembly 5, as indicated in FIGS. 4A, 4B, and 4C, which respectively show a front view, with cover and diaphragm removed, and sectional views along two axial planes, disposed at right angles to each other.

The regulator assemblage comprises a hollow cylindrical housing 42, which in the present embodiment takes the form of an aluminum shell one-sixteenth of an inch thick, and 3 5/8 inches in outer diameter. Set into one end of the housing 42 is a closure 40 which is circular in outline, having an outwardly protruding central portion which forms a diametrical channel 40a, one inch wide and nearly a half inch deep on the interior.

Rigidly connected in gastight relation to an opening near the center of the back side of channel 40a, as shown in FIG. 4C, is an aluminum connecting pipe 74, which is 1 1/8 inches in outer diameter and one-eighth inch in wall thickness. Pipe 74 leads off in a direction which is substantially normal to the principal longitudinal direction of the channel 40a, its axis being substantially parallel to the plane of the diaphragm 43, which will be described presently. Pipe 74 terminates in a flanged coupling 75, internally screw threaded, into which is fitted the screw-threaded head 76a of the matching pipe 76. The latter is fitted in gastight relation, inside the auxiliary hose 70 (shown in FIG. 3) which leads into that portion of the diver's mask 4 which fits directly over the mouth and nose of the diver. The life-supporting gas mixture brought in through intake valve 5a passes under a baffle 50, through the tube 85, and is inhaled through axially disposed inner tube 77a inside of connected pipes 74 and 76 leading to mask 4. Tubes 85 and 77a are about one-fourth inch in inner diameter and may be formed, for example, of aluminum. Carbon dioxide exhaled by the diver passes through the annular space 77b in the connected pipes 76 and 74, returning to the chamber 42, and ultimately to exhaust valve 5b.

At opposite ends of the channel 40a are circular openings 42b and 42c, about one-half inch and five-eighths of an inch in outer diameter, respectively, each of which is screw threaded internally, and flanged outwardly to accommodate matching flanges on the respective ends of the aluminum pipe fittings 44 and 45, which are also internally screw threaded. Pipe 44 is five-eighths of an inch in outer diameter, has an overall wall thickness of one-eighth of an inch, and extends three-eighths of an inch out from the base of channel 40a. Pipe 45, on the diametrically opposite side, is about three-quarters of an inch in outer diameter and also has an overall wall thickness of one-eighth of an inch. The aluminum pipe fittings 44 and 45 are respectively designed to receive the left-hand, screw-threaded ends 46a and 47a of a pair of pipe housings 46 and 47 which respectively house the valve assemblages 5a and 5b.

The aluminum pipe coupling 46 forms a leg which extends outwardly about 1 1/2 inches from the bottom of channel 40a, and serves to connect the intake hose 6a to the interior of housing 42 which encloses valve 5a. The inner end 46a of coupling 46 is a cylindrical fitting, one-half inch in diameter and three-eighths of an inch long, designed to screw into the pipe fitting 44. To the right of fitting 46a is a one inch diameter flange 46b, one-quarter of an inch long. Pipe 46 terminates in an outwardly extending cylindrical protrusion 46c which is three-fourths inch long and three-fourths inch in diameter, and externally screw threaded to form a gastight connection with the hose 6a. The coupling 46 has an internal channel which decreases in diameter from five-eigths inch at its outer end in contact with the hose 6a, to three-eighths inch in the first quarter inch of its length, the diameter remaining uniform for the next three-eighths of an inch to form a cylindrical chamber 61. The internal diameter is again slightly reduced, providing a sleeve 58, about seven-eighths inch in diameter and one-half inch long, in which the valve head 49 moves between open and closed positions.

To the left of the sleeve 58, the channel is narrowly constricted slanting inwardly at about a 45.degree. angle to form the valve seat 58b to the left of which is a tubular channel 58a about one-eighth inch in diameter. The valve head 49, which is designed to move slidably to-and-fro along the cylindrical channel 58, is cylindrical at its outer end, slanting inwardly to a stem portion 48, about one-sixteenth inch in diameter. The head 49 has an inwardly slanted portion, designed to mate with valve seat 58b. The inwardly slanted portion has an annular notch into which a ring of neoprene, or other suitable elastomer, is mounted in such a manner that it is compressed against the mating edge of valve seat 58b when valve 5a is closed. The valve stem 48, which extends seven-sixteenths inch to the left of the head 49, passes through a chamber 54, which serves as an outlet for gas passing through when the valve is open. The left-hand end of valve stem 48 is screwed or otherwise rigidly secured axially in a piston 53, slidably mounted to move to-and-fro in a sleeve 53a under control of lever arm 55, which, in turn, is actuated by the motion of diaphragm 43 to be presently described. This motion actuates the cam member 55a to rotate about a one-sixteenth inch diameter stainless steel roll pin 56 in the bearing 57, actuating valve 5a to open and close. In order to prevent the diver from constantly breathing in exhaled carbon dioxide, the baffle 50, about three-fourths inch long, 1 inch wide and one-sixteenth inch thick, projects inwardly in a plane substantially parallel to diaphragm 43, forming a cavity below its surface about one-fourth inch wide and 1 inch long. A tube 85 carries the inhaled life support gas from the vicinity of intake valve 5a to the inner tube 77a of tube 74 to 76, leading to the diver's mask 4.

Exhaust valve 5b comprises the coupling 47 which protrudes about 11/2 inches to the right of the base member 40. The left-hand end of coupling 47 comprises a cylindrical externally screw-threaded portion 47a, which is five-eighths inch in outer diameter, and five-eighths inch long, and screws into the leg 45. Concentric with the outer end of section 47a is a flanged portion 47b, which is 1 inch in diameter and one-fourth inch wide. The screw-threaded outer end 47c of coupling 47 has an outer diameter of about three-fourths inch, and extends outwardly three-fourths inch from flange 47b. End 47c is adapted to screw into the exhaust hose 6b. At the right-hand end, coupling 47 has an inner diameter of three-fourths inch, which is sharply constricted in the first quarter inch of its length to five-eighths inch, a diameter which remains uniform for five-eighths inch, moving left, to form the cylindrical chamber 66. At a plane seven-eighths inch from the right-hand end of coupling 47, the inner diameter is again sharply constricted to form a 1/4-inch diameter 64 extending one-eighth inch beyond the constriction. As one moves left, chamber 64 is enlarged in diameter forming an annular surface slanting outwardly at about 45.degree. with the horizontal, thereby forming valve seat 47d to the left of which is cylindrical chamber 64a, of 3/8-inch diameter, in which the valve head 63 is slidably moved to-and-fro.

Valve head 63 is cylindrical at its left-hand end, having about a slight clearance with the curved inner surface of chamber 64a. The right-hand end, which is designed to form a mating relationship with valve seat 47c, is conical in shape, being rounded at the end, and sharply notched to accommodate O-ring 65, about one-eighth inch in diameter, comprising neoprene or other suitable elastomer, which is compressed against the valve seat 47c when the valve is closed. The valve head 63 is moved to-and-fro in channel 64a by means of the axially disposed stem 62, which is one-sixteenth inch in diameter and seven-eighths inch long. The stem 68 slides back and forth in the sleeve 68a in the bearing 68, which is mounted in the left-hand end of the channel 64. Bearing 68, which is three-eighths inch in diameter, and about one-fourth inch deep, fills about half of channel 64a, leaving about five thirty-seconds inch for the to-and-fro motion of valve head 63. Bearing 64 has several longitudinal bores 64a, about one-sixteenth inch in diameter, for admitting exhaust fluid into the channel 64a. The inner end of bearing 68 has an annular recess about one-eighth inch deep and spaced in a radial direction about one thirty-second inch out from sleeve 68a, which accommodates near its outer surface an annular gasket ring 69, about one thirty-second inch thick and one-sixteenth inch in radial extent, which is fitted into place in a recess in the inner wall of the screw-threaded member 47a, to hold the bearing 68 in place. Between bearing 68 and the valve head 63 are connected a pair of springs of sufficient tension to maintain valve 5b in normally closed position.

The valve stem 62 has screwed onto its left-hand end, a partially cylindrical projection 67 which is rounded on one end to a radius of about one-eighth inch. This fits into notches 73c and 73d (not shown) of slightly larger radius, near the outer ends of each of the twin lever arms 73a, 73b which are fastened near their outer ends to rotate about the one-sixteenth-inch diameter stainless steel roll pin 71, whose ends are supported in two small bearings fastened to the interior of shell 42, at positions slightly spaced apart. At their inner ends, levers 73a and 73b have twin cylindrical projections which serve as a pair of parallel bearings in which the one-sixteenth-inch diameter roll pin 58 is rotated. The bearings are in contact with the underside of diaphragm 43, thereby serving to couple the motion of the diaphragm 43 through lever arms 55 and 73a, 73b, to respectively operate intake valve 5a and exhaust valve 5b, as will be explained.

The diaphragm 43 is circular, 4 inches in diameter, and is formed of a film one thirty-second inch thick of what is known in the art as "dental rubber." This may comprise, for example, pure gum rubber. To this is bonded, concentrically, a circular stainless steel plate 43a, one thirty-second inch thick and 2 3/4-inch in diameter, by use of a bonding agent comprising, a silicone-based cement, such as, for example, RTV-108 ADHESIVE, manufactured by the General Electric Company.

The diaphragm 43 is held taut by compression between the flanges 42a of the housing 42 and 41a of the mating closure 41, which form between them 1/4-inch annular ring at the edge of the diaphragm. The closure 41 is of aluminum, a shell one-sixteenth-inch thick, 3 five-eighths inch in diameter and one-half inch deep, except for the center of the front, which is bowed slightly outward to a depth of about three-eighths inch, and includes 3 perforations, three-sixteenths inch wide. A convolute 43b, which is three sixty-fourths inch in diameter, is formed integrally as a part of the rubber, with the diaphragm 43 and fits against the inner edge of the closure 41 to provide spring action against which the diaphragm 43 is moved to the left in response to internal pressure. A V-type retainer, ring shaped, coupling 60 formed, for example, of stainless steel, one-sixteenth inch thick, is fitted tightly over the junction between the flanges 41a and 42a to hold them rigidly in place in a fluidtight junction with the edge of diaphragm 43.

Near the center of the stainless steel plate 43a is rigidly fastened the flat portion 59a of yoke 59, so that its legs are substantially parallel to and centered in the channel 40a. Flat portion 59a extends thirteen sixty-fourths inch across the width of channel 40a and seven sixty-fourths inches along the channel, its inner edge being displaced seven sixty-fourths inch from the center in the plane of the diaphragm. At the end of the soldered portion, the yoke executes two right-angle bends, to form a two-pronged projection which extends parallel to and three-sixteenths inch above the surface of the diaphragm plate 43a. The prongs 59b and 59c are each three-sixteenths inch wide, about five-eighths inch long, and spaced apart seven thirty-seconds inch. The lever 55, which is 2 inches long and one-eighth inch wide, is connected at one end to rotate about roll pin 56, the other end projecting between the lever arms 73a and 73b, and bearing against roll pin 58. Thus, lever arm 55 is actuated to rotate about the pin 56 by motion of diaphragm 43. This, in turn, controls the motion of cam 55a against piston 53, depending on which way the diaphragm 43 moves.

Thus, when the diver breathes out, the diaphragm 43 moves to the left to the position indicated by the dotted lines on FIG. 4B, permitting lever 55 and cam 55a to rotate in a clockwise direction about the roll pin 56. This closes intake valve 5a by permitting the piston 53 to move to the left, seating valve head 49 by compressing O-ring 51 against the valve seat 58b. At the same time, the twin levers 73a, 73b (not shown) are moved counterclockwise by the motion of yoke 59 connected to the diaphragm. This operation moves the valve head 63 and O-ring 65 off of the valve seat 47d, thereby opening the exhaust valve 5b, permitting the exhaust gases to be expelled.

When the diver breathes in, the diaphragm returns to the normal position shown in full line in FIG. 4B. The counterclockwise rotation of lever arm 55 moves cam 55a against the piston 53, whereby the valve head 49 and O-ring 51 are forced off of the valve seat 58b, opening valve 5a. The twin lever arms 73a, 73b are simultaneously moved in a clockwise direction, permitting valve head 63 to reseat on valve seat 47d against O-ring 65, closing exhaust valve 5b during the intake portion of the cycle.

In case the gas supply based on land, or in the diving bell 3, should fail, means is provided for connecting the emergency auxiliary source 36 (shown in the schematic of FIG. 2) to the mask 4 through the junction 39. Upon manual operation of the valve 38 by the diver the gas from auxiliary source 36 flows through valves 37 and 38 to the junction 39. Back pressure actuates the valve 78 to close off the normal intake hose 6a. The auxiliary gas then flows to the mask 4 through the demand regulator 5 in the manner previously described.

To recapitulate, it is contemplated that the chamber 3, through which a demand regulator system in accordance with the present invention will operate, will be submerged at depths of from 200 to 600 feet below the surface of the sea, and that the diver 2, as shown in FIG. 1, will have swimming freedom to ascend approximately 15 feet above the chamber or descend to 50 feet below the chamber at any particular submerged depth. This last-mentioned range can be extended by using a compressor of higher capacity. The demand regulator system should be designed to operate at a flow capacity for life-supporting gas of 1 to 5 actual cubic feet per minute at the diver's temperature range, which, it is contemplated, would be approximately 80.degree.--90.degree. Fahrenheit.

The requirements for the demand regulator 5, in preferred form, are as follows:

The inhalation valve 5a is preferably designed to accommodate a flow of from 1 to 5 actual cubic feet per minute, and to open at a suction pressure of one-fourth inch of water.

The supply pressure to the regulator 5 is preferably maintained at 75 pounds per square inch above the ambient pressure of the chamber 3; however, the pressure drop across the input valve 5a to regulator 5 will vary, depending on the diver's position relative to the submerged chamber 3.

The exhalation valve 5b will preferably open in response to a positive pressure of 1 inch of water above the diver's ambient pressure. The regulator downstream pressure is preferably maintained at between 30 and 40 pounds per square inch below the ambient pressure of the chamber of regulator 5. However, the pressure drop across the exhaust valve 5bof the regulator will vary, depending on the diver's depth with relation to the submerged chamber 3.

It will be understood by those skilled in the art that the present invention is not limited to the specific form or structures described herein by way of illustration; but that the scope of the invention is defined in the appended claims.

Claims

I claim:

1. A closed-cycle breathing apparatus comprising in combination a breathing mask constructed and arranged to surround in gastight relation that portion of the person of the breather including his mouth and nose and including regulator means to control the flow of gas to and from said breathing mask in accordance with the breathing demands of said breather, a source of breathing gas, compressor means, and decompressor means, and conduit means for connecting said source through said compressor means to said mask under control of said regulator means, and to return the exhaust gas from said mask through said decompressor means under control of said regulator means, said conduit means comprising an inner conduit surrounded by an outer conduit, said inner conduit conveying breathing gas to the mask, said outer conduit conveying exhaust gas from the mask, each of said conduits having one end in free communication with the interior of said mask and having the other end under the control of said regulator means, said regulator means comprising in combination with said mask, a chamber, one wall of said chamber assuming the form of a flexible diaphragm, an intake valve and an exhaust valve, means comprising a system of levers coupled to said diaphragm and constructed and arranged to open said intake valve and close said exhaust valve upon inspiration of said breather, and to close said intake valve and open said exhaust valve upon expiration of said breather, said system of levers coupled to said diaphragm comprising a pair of levers, each pivotally mounted to rotate about fixed pivot means on said regulator means and each having a surface constrained to move with the surface of said diaphragm, the two levers constrained in response to the motion of said diaphragm to rotate in opposite directions about their respective fixed pivot means, each of said levers coupled at its outer end adjacent the fixed pivot means to control the to-and-fro motion of the valve stem of a respective one of said intake and exhaust valves, whereby upon inspiration and expiration, one of said levers rotates in a clockwise direction to move one of said valves and the other of said levers moves in a counterclockwise direction to move the other of said valves.

2. The combination for a submerged diver in accordance with claim 1 wherein said compressor means and said decompressor means are housed in a life support chamber.

3. The combination in accordance with claim 2 including an auxiliary source of breathing gas adjacent the person of said diver, and means under manual control of said diver for connecting said auxiliary source to said mask

through said regulator means. 24. The combination in accordance with claim 2 wherein said life support chamber is a diving bell constructed to accommodate at least one diver in a watertight environment during trips from and to the water surface to a selected level below the surface and to permit egress and ingress of the diver from said bell at said selected level, and wherein said conduit means further comprises hoses for

connecting said diver to and from said diving bell. 5. The combination in accordance with claim 1 wherein said source of breathing gas is a mixture of a major portion of helium and the balance consisting essentially of

oxygen and nitrogen. 6. The combination in accordance with claim 5 wherein said source of breathing gas is a mixture of about 66 percent helium, 25

percent nitrogen, and 9 percent oxygen. 7. The combination in accordance with claim 5 wherein said source of breathing gas is a mixture of about 85

percent helium, 11 percent nitrogen, and 4 percent oxygen. 8. A closed-cycle breathing apparatus comprising in combination a breathing mask constructed and arranged to surround in gastight relation that portion of the person of the breather including his mouth and nose and including regulator means to control the flow of gas to and from said breathing mask in accordance with the breathing demands of said breather, a source of breathing gas, compressor means, and decompressor means, and conduit means for connecting said source through said compressor means to said mask under control of said regulator means, and to return the exhaust gas from said mask through said decompressor means under control of said regulator means, said regulator means comprising in combination with said mask, a chamber, one wall of said chamber assuming the form of a flexible diaphragm, an intake valve and an exhaust valve, means comprising a system of levers coupled to said diaphragm and constructed and arranged to open said intake valve and close said exhaust valve upon inspiration of said breather, and to close said intake valve and open said exhaust valve upon expiration of said breather, wherein said system of levers coupled to said diaphragm comprises a yoke rigidly connected near the center of the flexible wall of said diaphragm on the inside of said chamber, said yoke including a pair of prongs extended in a plane substantially parallel to and slightly spaced apart from the surface of said diaphragm, a first roll pin supported to roll with its two ends bearing on the respective inner surfaces of said prongs facing said diaphragm, a pair of twin levers disposed in parallel planes transverse to the plane of said diaphragm, said twin levers spaced apart a lateral distance which is less than the spacing between said prongs, said twin levers respectively terminating at the ends thereof near the center of said diaphragm in a pair of rounded projections which bear against the inner surface of said diaphragm, said rounded projections respectively accommodated between said prongs and forming bearings supporting said first roll pin, a second roll pin mounted in a pair of twin bearings fastened to the inner wall of said chamber at the periphery of said diaphragm, said twin levers being fastened at their respective outer ends to rotate about said second roll pin in a direction determined by the direction of motion of said diaphragm, said twin levers having respective semicircular notches in matched positions near the outer ends thereof, a semicylindrical member symmetrically supported in said notches, said exhaust valve having a stem connected to said semicylindrical member between said notches, the combination including said twin levers, said semicylindrical member and said valve stem constructed and arranged to open said exhaust valve in response to rotation of said twin levers in one direction about said second roll pin and to close said exhaust valve in response to rotation of said twin levers in the opposite direction about said second roll pin, a single lever extending transversely to the plane of said diaphragm and directed in a substantially diametrically opposite direction to the direction of said twin levers, the inner end of said single lever projecting between the rounded projections of said twin levers and bearing against the central portion of said first roll pin, a third roll pin mounted in a bearing fastened to the inner wall of said chamber at the periphery of said diaphragm in a position substantially diametrically opposed to the positions of said twin bearings, said single lever fastened at its outer end to rotate about said third roll pin as determined by the direction of motion of said diaphragm, a cam connected to the outer end of said single lever, said cam constructed to bear against the face of a member rigidly connected to the valve stem of said intake valve, the combination including said single lever, said cam, said member and said valve stem, constructed and arranged to open said intake valve in response to rotation of said single lever about said third roll pin in one direction and to close said intake valve in response to the rotation of said single lever about said third roll pin in the opposite direction.